aron Sheehan-Dean is the Fred C. Frey Professor of Southern Studies at Louisiana State University, where he teaches courses on nineteenth-century U.S. history, the Civil War and Reconstruction, and Southern History. He is the author of Why Confederates Fought: Family and Nation in Civil War Virginia, the Concise Historical Atlas of the U.S. Civil War, and the editor of several books. His latest research project, The Calculus of Violence: How Americans Fought the Civil War will be published in Fall 2018. At least three-quarters of a million lives were lost during the AmericanCivil War. Given its seemingly indiscriminate mass destruction, thisconflict is often thought of as the first “total war.” But Aaron Sheehan-Dean argues for another interpretation.The Calculus of Violence demonstrates that this notoriously bloody war could have been much worse. Military forces on both sides sought to contain casualties inflicted on soldiers and civilians. In Congress, in church pews, and in letters home, Americans debated the conditions under which lethal violence was legitimate, and their arguments differentiated carefully among victims—women and men, black and white, enslaved and free. Sometimes, as Sheehan-Dean shows, these well-meaning restraints led to more carnage by implicitly justifying the killing of people who were not protected by the laws of war. As the Civil War raged on, the Union’s confrontations with guerillas and the Confederacy’s confrontations with black soldiers forced a new reckoning with traditional categories of lawful combatants and raised legal disputes that still hang over military operations around the world today. In examining the agonizing “just war” debates of the Civil War era, Sheehan-Dean discards conventional abstractions—total, soft, limited--as too tidy to contain what actually happens on the ground.